Tank filtration apparatus containing hollow fiber membrane cartridge

ABSTRACT

A hollow fiber membrane cartridge comprises a bundle of a plurality of hollow fiber membranes, both ends of which are fixed by adhesion, a cartridge head fixed at the periphery of the bundle at one end so as not to permit the passage of liquid either in or out, and a bottom ring fixed at the periphery of the bundle at the other end so as not to permit the passage of liquid either in or out, wherein the cartridge head and the bottom ring are not connected and fixed but are separated, the hollow portion at the end of each hollow fiber membrane on the cartridge head side is open, the hollow portion at the end of each hollow fiber membrane on the bottom ring side is sealed, and a plurality of through-holes are provided in an adhesion and fixation layer on the bottom ring side.

TECHNICAL FIELD

The present invention relates to a filtration cartridge using hollowfiber membranes which is set in a tank type filtration apparatus or arack type filtration apparatus. More particularly, the present inventionrelates to a hollow fiber membrane cartridge used in a filtrationapparatus for removing turbidity and bacteria from a large volume of rawwater such as river water, lake water, underground water, sea water,life waste water or industrial waste water.

The present invention relates also to a tank type or rack typefiltration apparatus using the above-mentioned hollow fiber membranecartridge(s).

BACKGROUND ART

JP-A-61-153104 discloses, as a conventional cartridge using hollow fibermembranes, the cartridge shown in FIG. 3 which has the followingstructure: a plurality of hollow fiber membranes are accommodated in acylindrical casing, both ends of each hollow fiber membrane are fixed tothe cylindrical casing in upper and lower, respectively, adhesion andfixation portions, and the cylindrical casing is a casing integrallymolded so as to extend to the upper and lower ends of the hollow fibermembranes. The hollow portions of a large number of the hollow fibermembranes are open in the upper adhesion and fixation portion of thecartridge but are sealed in the lower adhesion and fixation portion, andan adhesive layer in the lower adhesion and fixation portion has aplurality of through-holes. An air chamber surrounded by the cylindricalcasing is formed under the lower adhesion and fixation portion.

This hollow fiber membrane cartridge is for filtration under externalpressure and is used after being set in a filtration column. Whenmaterials incapable of permeating the membranes are accumulated on theouter surfaces of the membranes, the filtering capability of themembranes is deteriorated, and therefore a washing procedure forremoving the accumulated materials on the surfaces of the membranes iscarried out after filtration for a definite time.

A method for washing called air bubbling is known. This method comprisesthe steps of introducing air into the hollow fiber membrane cartridgethrough its lower portion in a filtration column filled with raw water,and vibrating the hollow fiber membranes in a gas-liquid mixed fluid topeel off the accumulated materials on the surfaces of the membranes.

However, in the hollow fiber membrane cartridge, air bubbling does notpermit sufficient washing in some cases because both ends of each hollowfiber membrane are fixed to the cylindrical casing, so that thevibration of the hollow fiber membranes is limited. This phenomenon isremarkable and causes troubles in some cases in a long-term filtrationoperation, particularly when the outside diameter of the cartridge islarge.

DISCLOSURE OF THE INVENTION

In order to solve such problems, the present invention is intended toprovide a hollow fiber membrane cartridge which facilitates thepeeling-off of suspended materials accumulated on the outer surfaces ofhollow fiber membranes by enabling each hollow fiber membrane to vibrateas much as possible at the time of washing by air bubbling, and permitseasy discharge of the peeled-off suspended materials from the hollowfiber membrane cartridge.

That is, the present invention relates to a hollow fiber membranecartridge comprising a bundle of a plurality of hollow fiber membranes,both ends of which are fixed by adhesion, a cartridge head fixed at theperiphery of the bundle at one end so as not to permit the passage ofliquid either in or out, and a bottom ring fixed at the periphery of thebundle at the other end so as not to permit the passage of liquid eitherin or out, wherein the cartridge head and the bottom ring are notconnected or fixed but are separated. The hollow portion at the end ofeach hollow fiber membrane on the cartridge head side is open, thehollow portion at the end of each hollow fiber membrane on the bottomring side is sealed, and a plurality of through-holes are provided in anadhesion and fixation layer on the bottom ring side. In one embodimentof the present invention, the end of the bottom ring is fixed byadhesion to the periphery of the bundle of the hollow fiber membranes soas to extend out beyond the end of the bundle of the hollow fibermembranes.

When the above-mentioned structure according to the present invention isemployed, each hollow fiber membrane can be vibrated with maximumamplitude in a permissible range because no cylindrical casing coveringthe whole hollow fiber membranes is present at the periphery of thehollow fiber membrane cartridge. As a result, suspended materialsaccumulated on the outer surfaces of the hollow fiber membranes becomeeasy to peel off at the time of washing by air bubbling, and thesuspended materials peeled off become easy to discharge from the hollowfiber membrane cartridge. Therefore, the filtering capability can bemaintained stably for a long period of time.

In addition, when the end of the bottom ring of the hollow fibermembrane cartridge is fixed by adhesion so as to extend out beyond theend of the bundle of the hollow fiber membranes, gas for air bubblingcan be reserved inside the bottom ring and hence can be efficientlyconducted to the hollow fiber membranes through the through-holesprovided in the adhesion and fixation layer on the bottom ring side, sothat washing by air bubbling can be satisfactorily carried out.

Furthermore, the present invention relates to a tank type or rack typefiltration apparatus using the above-mentioned hollow fiber membranecartridge(s).

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional illustration showing one embodiment of the hollowfiber membrane cartridge of the present invention supported in asuspended state in a tank type filtration apparatus.

FIG. 2 is an enlarged view of the principal part showing the structureof the bottom ring adhesion and fixation portion of the hollow fibermembrane cartridge.

FIG. 3 is a schematic illustration of a well-known hollow fiber membranecartridge.

FIG. 4 is a sectional illustration showing one embodiment of the hollowfiber membrane cartridge of the present invention fixed by suspensionfrom a treated water header piping in a tank type filtration apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the hollow fiber membrane cartridge of the presentinvention is explained below with reference to the drawings.

FIG. 1 is a sectional illustration showing one embodiment of the hollowfiber (yarn) membrane cartridge of the present invention supported in asuspended state in a tank type filtration apparatus. FIG. 2 is anenlarged view of the principal part for explaining the structure of thebottom ring adhesion and fixation portion of the hollow fiber membranecartridge.

In FIG. 1, the hollow fiber membrane cartridge 4 of the presentinvention is composed of a large number of hollow fiber (filament)membranes 3, an adhesion and fixation layer 11, a cartridge head 12, anadhesion and fixation layer 14 and a bottom ring 13. At one end of abundle of the hollow fiber membranes 3, the hollow fiber membranes areintegrally bonded to one another with an adhesive and are integrallyattached to the inside of the cartridge head 12 to form the adhesion andfixation layer 11. The ends of the hollow fiber membranes 3 on thecartridge head 12 side are open.

At the other end of the bundle of the hollow fiber membranes 3, thehollow fiber membranes are integrally bonded to one another with anadhesive and are integrally attached to the inside of the bottom ring 13to form the adhesion and fixation layer 14. The ends of the hollow fibermembranes 3 on the bottom ring 13 side, however, are sealed. As shown inFIG. 2, a plurality of through-holes 14 a are formed in the adhesion andfixation layer 14 in order to introduce raw water or gas for washinginto the bundle of the hollow fiber membranes and bring the raw water orthe gas effectively into contact with the periphery surface of eachhollow fiber membrane.

The diameter of the hollow fiber membrane cartridge 4 is 30 mm to 800mm, preferably 80 mm to 800 mm. The length of the hollow fiber membranecartridge 4 is chosen in a range of 300 mm to 3,000 mm.

In the present invention, the cartridge head 12 and the bottom ring 13are not connected or fixed but are separated. Therefore, no conventionalcylindrical casing is present at the periphery of the bundle of thehollow fiber membranes 3 between the cartridge head 12 and the bottomring 13, and substantially throughout this range, the hollow fibermembranes 3 are exposed. However, the periphery of the bundle of thehollow fiber membranes 3 may be covered with, for example, a flexibleresin net having large openings which does not limit the vibration ofthe hollow fiber membranes and does not substantially hinder the passageof a fluid. In this case, the net is not directly fixed to either thecartridge head 12 or the bottom ring 13 but is embedded in the adhesionand fixation layer 14 to be fixed. Damage to the hollow fiber membranes3 by conveyance can be prevented by covering the bundle of the hollowfiber membranes with the flexible net.

As the hollow fiber membrane 3 used in the present invention, reverseosmosis membranes, nanofiltration membranes, ultrafiltration membranesand microfiltration membranes can be used from the viewpoint of poresize. A material for the hollow fiber membrane 3 is not particularlylimited and includes polysulfones, polyether sulfones,polyacrylonitriles, polyimides, polyether imides, polyamides, polyetherketones, polyether ether ketones, polyethylenes, polypropylenes,poly(4-methylpentene)s, celluloses, cellulose acetates, poly(vinylidenefluoride)s, ethylene-tetrafluoroethylene copolymers,polytetrafluoroethylenes, etc. Composite materials thereof can also beused. As to the shape of the hollow fiber membrane, hollow fibermembranes having an inside diameter of 50 μm to 3,000 μm and a ratio ofinside diameter to outside diameter of 0.3 to 0.8 can be used.

The adhesive used in the present invention includes polymeric materialssuch as epoxy resins, urethane resins, epoxyacrylate resins, siliconeresins, etc. A method for the adhesion includes well-known methods suchas centrifugal adhesion method, still-standing adhesion method, etc.When the curing shrinkage and strength of the adhesive are desired to beimproved, a fibrous material such as glass fiber or carbon fiber, orfine powder of carbon black, alumina, silica or the like may beincorporated into the above-exemplified adhesive.

Materials for the cartridge head 12 and the bottom ring 13 used in thepresent invention are not particularly limited and may be the same ordifferent. Thermoplastic resins and stainless steel are preferably usedas the materials. As the thermoplastic resins, there are usedpolyethylenes, polypropylenes, poly(4-methylpentene)s, poly(vinylchloride)s, poly(vinylidene fluoride), ethylene-tetrafluoroethylenecopolymers, polytetrafluoroethylenes, polycarbonates,acrylonitrile-butadiene-styrene copolymers (ABS), polyphenylene ethers,polysulfones, polyether sulfones, polyether imides, polyamides,polyether ketones, polyether ether ketones, etc. As the stainless steel,SUS304, SUS316, etc. are used.

The cartridge head 12 serves not only as a fixation portion forsuspending the hollow fiber membrane cartridge 4 in a tank typefiltration apparatus or a rack type filtration apparatus but also as asealing portion for separation between raw water and filtered water.Therefore, the cartridge head 12 is produced in a shape suitable for thesuspension, the fixation and the structure of a seal. For example, alevel difference, a groove or a collar projecting outside in thedirection of diameter may be provided at the periphery of the cartridgehead 12. Although the shape of section in the direction of diameter ofthe cartridge head 12 may be round, square, hexagonal, oval or the like,it is preferably round from the viewpoint of sealing properties betweenthe cartridge head 12 and an adhesion and fixation portion therefor andease of production of a filtration tank.

The through-holes 14 a provided in the adhesion and fixation layer 14 onthe bottom ring side in the present invention are holes made in theadhesion and fixation layer itself. As to the size of the through-holes,their equivalent diameter is chosen in a range of 2 mm to 30 mm. Here,the equivalent diameter is defined as 4×(sectional area of flowpath)/(circumference). The shape of the through-holes is selected frompolygons (e.g. triangle, tetragon and hexagon), a round shape, an oval,a fan shape, a C shape, a star shape, etc. Although the number of thethrough-holes is dependent on the sectional area of the cartridge andthe number of fibers, it is 2 to 300. As to the positions of thethrough-holes, the through-holes are preferably formed as follows: whenan explanation is given by taking the case of a certain adhesion andfixation section, the through-holes are dispersed on the adhesion andfixation section, for example, at the intersections of multiplexedcircles and radial lines, the intersections of lattices, or the apexesof a large number of equilateral triangles. It is especially preferableto form many of the through-holes in the central portion of the bundleof the hollow fiber membranes.

In the present invention, the bottom ring 13 is preferably fixed at theperiphery of the bundle of the hollow fiber membranes so as to jut outbeyond the ends of the hollow fiber membranes 3, to form an air chamber14 b surrounded by the adhesion and fixation layer and the bottom ring.Although the length of a portion of the bottom ring 13 which juts outfrom the ends of the hollow fiber membranes is dependent on the diameterof the cartridge, the volume of a gas supplied and the diameter andnumber of the through-holes, it is preferably 5 mm to 200 mm forpreventing dispersion and loss of the gas. When said portion is toolong, the total length of the cartridge is undesirably long, resultingin the formation of a useless space. When said portion is too short, thegas supplied to the cartridge is undesirably dispersed and lost in thelateral direction without being effectively introduced into thethrough-holes.

The shape of section in the direction of diameter of the bottom ring 13may be round, square, hexagonal, oval or the like. When the cartridge isset in a filtration tank, the shape of section is preferably the same asthat of the cartridge head, and a round shape is especially preferableas the shape of section.

The hollow fiber membrane cartridge of the present invention can beproduced as follows. A bundle of hollow fiber membranes whose hollowportions have been stopped at one end of the bundle is inserted into acartridge head 12, and an adhesive is introduced into the cartridge head12 to adhere and fix the hollow fiber membranes to one another andadhere and fix the bundle of the hollow fiber membranes to the cartridgehead 12, so as not to permit the passage of liquid either in or out. Thehollow fiber membranes and the adhesion and fixation layer are cuttogether to open the ends of the hollow fiber membranes. The other endsof the hollow fiber membranes are inserted into a bottom ring 13 withoutstopping their hollow portions, and a predetermined rod, pipe or platefor forming through-holes 14 a is set in the bundle of the hollow fibermembranes. Then, an adhesive is introduced into the bottom ring 13 toadhere and fix the hollow fiber membranes to one another and adhere andfix the bundle of the hollow fiber membranes to the bottom ring 13. Inthis case, the hollow portions at the ends of hollow fiber membranes aresealed with the adhesive at the same time. Thereafter, the rod, pipe orplate for forming through-holes 14 a is taken out of the adhesion andfixation layer to form through-holes 14 a. The following is alsopossible: a rod, pipe or plate for forming through-holes 14 a is set inthe bundle of the hollow fiber membranes, followed by adhesion andfixation, and the instrument for forming through-holes 14 a is takenout, after which a bottom ring 13 is fixed at the periphery of theadhesion and fixation layer by adhesion or welding.

An example of tank type filtration apparatus (FIG. 1) comprising thehollow fiber membrane cartridges of the present invention suspended andfixed therein is explained below.

In FIG. 1, numeral 1 denotes a tank type filtration apparatus forfiltering raw water fed, which can be used for water treatment inreducing turbidity and bacteria from a large volume of raw water such asriver water, lake water, underground water, sea water, life waste wateror industrial waste water.

The filtration tank 2 of the tank type filtration apparatus 1 iscomposed of a tank main body 2 a and a lid 2 b, and a separation plate 5and a partition plate 6 are fixed on the inner wall of the tank mainbody 2 a at predetermined heights, respectively, by welding or the likeso as not to permit the passage of liquid either in or out. A feed waterchamber 7 is formed of a space formed by the lower portion of the tankmain body 2 a and the separation plate 5, and a feed water chamber 8 isformed of a space formed by the middle portion of the tank main body 2a, the separation plate 5 and the partition plate 6. A treated waterchamber 10 is formed of a space formed by the partition plate 6 and thelid 2 b through a packing 9.

As described above, the inside of the filtration tank 2 is divided intothe three chambers by the separation plate 5 and partition plate 6 fixedin the filtration tank 2, and each hollow fiber membrane cartridge 4 ofthe present invention is suspended in the feed water chamber 8 with itsone end held by the partition plate 6.

The partition plate 6 holding the hollow fiber membrane cartridge 4suspended therefrom is made in a predetermined thickness so as to have asufficient strength to withstand a load applied by the hollow fibermembrane cartridge and water pressure. A plurality of through-holes 6 afor inserting the hollow fiber membrane cartridges 4 are formed atpredetermined positions of the partition plate 6.

In the lower portion of each through-hole 6 a of the partition plate 6,a projection 6 b jutting inside the through-hole 6 a in the direction ofdiameter is formed, and the lower end of the cartridge head 12 providedat the periphery at the upper end of the hollow fiber membrane cartridge4 is caught by the projection 6 b to suspend and hold the hollow fibermembrane cartridge 4. As another embodiment, the following is possible:a collar jutting outside in the direction of diameter is formed on thecartridge head, and its underside is brought into contact with the topsurface of the partition plate 6 through a gasket to suspend and holdthe hollow fiber membrane cartridge.

An O-ring 15 is fitted in a groove 6 c formed on the wall surface ofeach through-hole 6 a of the partition plate 6, and the outer wallsurface of the cartridge head 12 is bonded to the O-ring 15 by pressurewelding, whereby the cartridge head 12 is attached to the partitionplate 6 so as not to permit the passage of liquid either in or out. Agroove for fitting the O-ring 15 therein may be formed on the cartridgehead 12.

The upper edge face of the cartridge head 12 is moored by a mooringmember 16 which has been provided on the wall surface of eachthrough-hole 6 a of the partition plate 6 so as to be removable, wherebythe cartridge head 12 is fixed to the partition plate 6 and the hollowfiber membrane cartridge 4 is stably accommodated in the filtration tank2.

In the above structure, during filtration operation using the tank typefiltration apparatus 1, raw water fed into the feed water chamber 7through a feed water inlet 2 c provided in the lower portion of the tankmain body 2 a of the filtration tank 2 by means of a pump (not shown) isfed into the feed water chamber 8 through the nozzle 5 a of theseparation plate 5 to fill up the feed water chamber 8, and is thenconducted to the periphery surface of each hollow fiber membrane 3.

The raw water near the periphery of each hollow fiber membrane 3 isfiltered under pressure through the hollow fiber membrane 3 from theoutside to the inside, and the filtered water is introduced into thetreated water chamber 10 through the opened upper end of the hollowfiber membrane 3. The filtered water accommodated in the treated waterchamber 10 is taken out of the filtration tank 2 through a treated wateroutlet 2 d provided in the upper portion of the lid 2 b.

As another filtration operation method, a method can be adopted whichcomprises carrying out filtration by sucking air in the treated waterchamber 10 through the treated water outlet 2 d by means of a suctionpump (not shown) to reduce the pressure, while filling the feed waterchamber 8 with raw water.

When the hollow fiber membranes 3 are subjected to back washing with thefiltered water, the filtered water is supplied through the treated wateroutlet 2 d and allowed to flow backward into the feed water chamber 8 toremove suspended materials (materials incapable of permeating themembranes) accumulated on the outer walls of the hollow fiber membranes3, after which it is introduced into the feed water chamber 7 throughthe nozzle 5 a and then discharged from the filtration tank 2 throughthe feed water inlet 2 c.

When the hollow fiber membranes 3 are subjected to air bubbling, air issupplied at first to the feed water chamber 7 through an air inlet 2 fprovided in the lower portion of the tank main body 2 a, with the feedwater chamber 8 filled with raw water. The air whose pressure has beenadjusted in the feed water chamber 7 flows as bubbles into the feedwater chamber 8 filled with the raw water, through the nozzle 5 aprovided on the separation plate 5, and the air is conducted to the sideof the periphery of each hollow fiber membrane 3 from the bottom ring 13through the through-holes 14 a of the adhesion and fixation layer 14 tostir water in the bundle of the hollow fiber membranes 3 and vibrate thehollow fiber membranes 3. Thus, the air peels off the suspendedmaterials adhering to the surfaces of the hollow fiber membranes 3. Airaccumulated in the upper portion of the feed water chamber 8 isdischarged from the filtration tank 2 through an air outlet 2 g providedin the upper portion of the tank main body 2 a.

In the above air bubbling operation, for example, air, nitrogen gas oroxygen gas is supplied at first, with the feed water chamber 8 filledwith the raw water, namely, with the raw water being at rest and stayingin the feed water chamber 8. After air bubbling, the above-mentionedback washing operation is carried out to wash away the suspendedmaterials peeled off as described above, with filtered water suppliedthrough the treated water outlet 2 d. The filtered water containing thesuspended materials peeled off is discharged from the filtration tank 2through the nozzle 5 a provided on the separation plate 5, the feedwater chamber 7 and the feed water inlet 2 c, and accommodated in awaste water tank (not shown). Either the air bubbling operation or theback washing operation may be carried out at first, and the frequenciesof the back washing operation and the air bubbling operation arepreferably determined while monitoring the stability of the filtrationoperation.

In addition, an example of tank type filtration apparatus (FIG. 4)comprising the hollow fiber membrane cartridges of the present inventionsuspended from and fixed to a treated water header piping is explainedbelow.

In FIG. 4, each hollow fiber membrane cartridge 4 is suspended from andfixed to a branch pipe 18 branched from a treated water header piping17, by using a cartridge head collar 12 a provided at the periphery ofthe cartridge head 12 and a clamp 20 through a gasket 19.

In the above structure, during filtration operation using the tank typefiltration apparatus 1, raw water fed into a feed water chamber 7through a feed water inlet 2 c provided in the lower portion of the tankmain body 2 a of a filtration tank 2 by means of a pump (not shown) isfed into a feed water chamber 8 through the nozzle 5 a of a separationplate 5 to fill up the feed water chamber 8, and is then conducted tothe periphery surface of each hollow fiber membrane 3. The raw waternear the periphery of each hollow fiber membrane 3 is filtered underpressure through the hollow fiber membrane 3 from the outside to theinside, and the filtered water is introduced into the treated waterheader piping 17 through the opened upper end of the hollow fibermembrane 3 and the branch pipe 18. The filtered water in the treatedwater header piping is discharged from the filtration tank 2 through atreated water outlet 2 d provided in the tank main body 2 a.

The concentrated water not filtered through the hollow fiber membranes 3is discharged from the filtration tank 2 through a concentrated wateroutlet 2 g of the lid 2 b provided in the upper portion of thefiltration tank 2.

When the hollow fiber membrane cartridges 4 are subjected to airbubbling, air is supplied at first to the feed water chamber 7 throughan air inlet 2 f provided in the lower portion of the tank main body 2a, with the feed water chamber 8 filled with raw water. The air whosepressure has been adjusted in the feed water chamber 7 flows as bubblesinto the feed water chamber 8 filled with the raw water, through thenozzle 5 a provided on the separation plate 5, and the air is conductedto the side of the periphery of each hollow fiber membrane 3 from thebottom ring 13 through the through-holes 14 a of the adhesion andfixation layer 14 to stir water in the bundle of the hollow fibermembranes 3 and vibrate the hollow fiber membranes 3. Thus, the airpeels off the suspended materials adhering to the surfaces of the hollowfiber membranes 3. The air that has vibrated the hollow fiber membranes3 is discharged from the filtration tank 2 through an air outlet 2 gprovided in a lid 2 b.

Industrial Applicability

The hollow fiber membrane cartridge 4 of the present invention has nocylindrical casing attached to the periphery and hence can permitvibration of its hollow fiber membranes 3 as much as possible. Thus, theability to peel off suspended materials accumulated on the outersurfaces of the hollow fiber membranes 3 at the time of air bubblingoperation can be improved, and the suspended materials peeled off caneasily be discharged from the hollow fiber membrane cartridge 4.Furthermore, since a bottom ring 13 jutting out beyond the ends of thehollow fiber membranes 3 is provided at the lower end of the hollowfiber membrane cartridge 4 and through-holes 14 a are provided in anadhesion and fixation layer 14 on the bottom ring side, a gas suppliedcan be efficiently introduced into the bundle of the hollow fibermembranes. Therefore, when the cartridge of the present invention isused, air bubbling operation can be efficiently carried out, so that thefiltering capability of a filtration apparatus can be maintained stablyfor a long period of time.

What is claimed is:
 1. A tank filtration apparatus comprising afiltration tank, a separation plate, a treated water header piping,branch pipes branched from said treated water header piping, and ahollow fiber membrane cartridge, wherein said hollow fiber membranecartridge comprises a bundle of a plurality of hollow fiber membranes,both ends of which are fixed by adhesion, a cartridge head fixed at theperiphery of the bundle at one end so as not to permit the passage ofliquid either in or out, and a bottom ring fixed at the periphery of thebundle at the other end so as not to permit the passage of liquid eitherin or out, wherein the cartridge head and the bottom ring are notconnected or fixed to each other but are separated, and no cylindricalcasing covering the whole hollow fiber membranes is present, the hollowportion at the end of each hollow fiber membrane on the cartridge headside is open, the hollow portion at the end of each hollow fibermembrane on the bottom ring side is sealed, a plurality of through-holesare provided in an adhesion and fixation layer on the bottom ring side,said cartridge head has a collar at its periphery, and said hollow fibermembrane cartridge(s) is suspended from the branch pipe by its collar.2. A tank filtration apparatus according to claim 1, wherein the end ofthe bottom ring is fixed to the periphery surface of the bundle of thehollow fiber membranes so as to jut out beyond the end of the bundle ofthe hollow fiber membranes.